From Cobb's notes on which tune to use depending on available fuel: "These maps are designed for E10 fuel (fuel with 10% ethanol content). For those who only have access to E0 fuel (fuel with 0% ethanol) it is recommended to use the "91" and "ACN91" octane versions of the maps and datalog the car to ensure your fuel is performing to the necessary level. This is especially important for those using Canadian 94 octane E0 fuel."

As noted, here on the West Coast of Canada we can get 94 from Chevron (Standard Oil) but it is E0. This note from Cobb says I may only be able to use a 91 tune even though we can get 94 fuel here readily. And, it has me wondering if the car is actually better off running the 92 E10 available from Chevron in any event and with or without a tune (plus it's often 5 cents per litre less)?

 

The stock fuel trims on these cars is amazing.

it can tip in a very high percentage of fuel.

On a completely stock car, you can safely add 9 litres of E85 to a full tank.

On stage 1 Cobb you can safely add 12 litres of E85.

On stage 2 Cobb can can safely add 15 litres of E85.

Do not add any more than these numbers until you are custom tuned for it.

As always you mod at your own risk. Cobb are never going to suggest anything like this as people are unreliable. I say 12 litres for stage 1 and some moron will like it so much, and want more and do the wrong thing and add half a tank and lean out and have an issue and will want to sue someone for his own stupidity and claim he never put anymore than the amount.

So Cobb say none.

i have a custom tune for 50/50. Half E85 and half 98Ron (93Oct) .

Ran a 10.8 at the strip.

You’re welcome and don’t be a ******** and add more to any of these.

PS never put E85 in the tank if the car is going to sit for a month and not be driven. E85 does not store well.

 

Hey thanks for this 4.Z

 

Does anyone else have experience with this? I would be interested in others that have experience with this fuel mixture and their results.

 

For COBB OTS maps, follow their instructions. Do not add in additional E85. While some cars and systems can take it, it's not worth trying or experimenting. Get custom tuning done if you want to go that route. Ethanol requires higher volumes of fuel and without an ethanol content sensor and proper tuning, the ECU cannot add the required fuel. It's adding based on lambda outputs. The target lambda changes as well with different ethanol levels.

For those in Canada with 94 octane, run the ACN91 map. Sometimes they even call the maps ACN91/CAD94.

-Charles@BBi

 

^^ hey Charles, if running the ACN91 map I suppose we could use either E10% 92 or E0% 94, both available from Chevron?? Which is better?? Thanks, Doug

 

991.2 Can take it. The tip in is awesome from factory. What you are saying is correct for people wanting to run 40% + E85. With small amounts of E85, the ECU can easily add the extra fuel required.

I ran and tested this on my own car, prior to custom tune. I'm now custom tuned for 50% E85. I find that easy for top ups. I don't have flex fuel sensor, but I am custom tuned for it.

There will always be people who will do the wrong thing. You tell them 12 litres is safe. They put 12 litres in, and love the difference. But they always want more power. So they try a little more, and its great. And a little more, and they lean out and its great. And a little more and the lean right out and go Bang. Then they will claim they only ever put the 12 litres in. So, yes I understand why shops say Don't do any at all.

Morons should not try this at home. You do so under your own risk. Disciplined people who follow precise instructions, will be fine. More is not better, until you are custom tuned for it. YMMV.

 

Run the E10 92. That should run very close to a 93. You can always try both fuels, and you can view datalogs on how much timing is being pulled or look at knock events.

Be very careful. I do not advise. As mentioned, ethanol has different lambda targets, and the ECU simply does not know the ethanol content. You need a sensor. Good luck. Yes, ECU can add fuel but it doesn't know the correct ratios or blending that you created.

-Charles@BBi

 

APR has an e85 tune for the 991.2 and it runs wonderfully. I'd pass on the COBB tune.